Conventional photoresist development apparatus for the application of photoresist developer solutions to semiconductor wafers have been extensively used in the fabrication of semiconductor integrated circuits and are well known in the semiconductor processing industry. A conventional apparatus for applying a photoresist developer solution to a semiconductor wafer typically includes a photoresist development cup in which the semiconductor wafer is secured horizontally to receive the photoresist developer solution, typically from a developer dispense nozzle which applies droplets of the developer solution to the surface of the semiconductor wafer. In general, a wafer holder is connected to a motor which is typically attached to the base of the photoresist development cup such that the wafer can be spun by the motor during the photoresist development process. The wafer holder is positioned to hold the semiconductor wafer in a horizontal position. The photoresist development cup may further include a deflecting surface with a downward sloped surface immediately adjacent the edges of the wafer to drain excess photoresist developer solution from the surface of the wafer.
The conventional apparatus for applying a photoresist developer solution to a semiconductor wafer may also include a drip guard which usually has a flat annular surface on the top of the photoresist development cup to block drops of the photoresist developer solution dripping from the dispense nozzle when the nozzle moves between positions outside the cup and above the center opening in the flat annular drip guard. When the developer dispense nozzle is positioned directly above the center opening, it is able to move into the cup and to spray droplets of the developer solution onto the surface of the wafer.
The conventional flat strip guard is supposed to prevent excess drops of the photoresist developer solution dripping from the developer dispense nozzle from splashing onto the wafer. In practice, however, some of the photoresist developer solution caught by the conventional flat drip guard often drips from the edge of the drip guard back into the photoresist development cup, thereby allowing the surface of the wafer to accumulate an excess amount of the photoresist development solution. Furthermore, the excess photoresist developer solution dripping back into the photoresist development cup from the conventional flat drip guard often accumulates near the edge of the wafer, thereby causing an uneven distribution of the photoresist developer solution across the surface of the wafer.
Therefore, there is a need for a photoresist drip catching apparatus that prevents excess drops of the photoresist developer solution on the dispense nozzle from splashing onto the surface near the edge of the wafer after a desired amount of the photoresist developer solution has been applied to the surface of the wafer. Furthermore, there is a need to be able to drain the excess photoresist developer solution from the drip catching apparatus.